The Obama administration’s plans to energize the embattled agency that regulates the firearms industry and investigates gun violence are already running into trouble on Capitol Hill, foreshadowing the difficulties facing the president as he moves to advance his gun-control agenda.

President Obama announced his choice of B. Todd Jones to head the Bureau of Alcohol, Tobacco, Firearms and Explosives last month as a key element in his sweeping slate of gun proposals after the elementary school massacre in Newtown, Conn. Obama urged Congress to quickly confirm Jones in an effort to embolden an agency that has long operated with limited resources and a part-time director who splits his time between Minneapolis and Washington.

Since then, Senate Republicans have indicated they may block Jones’s appointment and have demanded to know more about his role in several operations and policy decisions. They have also expressed lingering suspicions about the agency, noting that it has been dogged by a series of debacles, some of them self-inflicted.

In the face of those obstacles, administration officials say they remain hopeful that the national debate over guns will compel the Senate to act on the nomination.

“It’s always been an uphill climb for any ATF nominee, but considering where we are at this moment in time, if there was going to be a confirmation, this is as best a time as ever,” said a Justice Department official who was not authorized to discuss the nomination publicly. “The landscape has changed. You have a lot more Democrats, and even some Republicans, who are saying, common-sense-wise, we need some reforms.”

The Washington Post’s Ed O’Keefe shows us some of the guns targeted by legislation that would outlaw certain rifles, pistols and high-capacity magazines. (The Washington Post)

Despite the growth of the gun industry and the U.S. population, the ATF has fewer than 2,500 agents, below what it had more than four decades ago. . The agency has a budget of about $1.1 billion. But ATF officials say the agency has the capacity to inspect only a fraction of the nation’s 60,000 retail gun dealers each year, with as many as eight years passing between store visits.

The lack of leadership has sapped morale at the agency, which Jones has attempted to revive since he became the agency’s part-time, acting director in September 2011.

“Todd Jones was dealing with the consequences of a broken agency,” said one ATF official who spoke on the condition of anonymity because he was not authorized to speak for the agency. “We had lost our way. He wanted to get us refocused on our core mission of fighting violent crime.”

It is unclear whether Jones, a federal prosecutor in Minnesota and a former Marine, will get the opportunity. Sen. Charles E. Grassley (Iowa), the ranking Republican on the Judiciary Committee, is demanding Justice Department documents and a formal interview with Jones before any hearing on his nomination.

Among other issues, Grassley and other lawmakers are demanding answers about the role Jones and his staff played in a flawed sting operation in Milwaukee and in a controversy in which Grassley has accused the Justice Department and city officials in St. Paul, Minn., of collusion.

“The White House waited nearly two years to name its last ATF nominee and then, when I requested additional information on his background, never responded and didn’t attempt to move him,” Grassley said. “Consequently, the ATF is rife with issues within its leadership. So it’s important that we get this nomination right, and it would help the process if the White House and Mr. Jones would provide the information we’re seeking on several issues that Mr. Jones has been involved in.”

The Justice Department official said the administration would cooperate with the committee to move the nomination forward.

For years, the ATF has been the stepchild of law enforcement — dismissed as a rogue agency by the National Rifle Association and other political opponents and enfeebled by the failure of successive administrations to secure the leadership and resources that agents say they need.

The NRA has lobbied successfully for decades to block all attempts to computerize records of gun sales, arguing against any kind of national registry of firearms ownership. For that reason, ATF researchers at the National Tracing Center in Martinsburg, W.Va., have to trace the paths of guns used in crimes with an antiquated, laborious process done mostly by hand. Instead of using a searchable computer database, the workers, using Scotch tape and magnifying glasses, scour ink-smeared, yellowed index cards and faded ledger books from gun stores. The center conducted 344,000 traces last year.

Over the years, officials have considered merging the ATF into another law enforcement agency, such as the FBI. As president, Ronald Reagan wanted to eliminate the agency and transfer its powers to the Secret Service and the Internal Revenue Service. The proposal to break up the ATF was floated again in the Justice Department last year, according to individuals in law enforcement.

The NRA has traditionally weighed in against such proposals, its leaders having decided they prefer a weak ATF to stronger new regulators, according to officials involved in discussions.

NRA spokesman Andrew Arulanandam disputed the suggestion that the organization wants an ineffective agency. “Our opposition is to some of the employees at ATF who view their mission and their job to harass and go after law-abiding gun owners,” he said. “They should go after people who are breaking the law.”

Arulanandam said the NRA would have nothing to say on Jones’s nomination until closer to any hearing.

Criticism of the ATF — and its toxic reputation with the gun lobby — recently prompted the agency to consider a rebranding effort. Amid congressional attacks last year over the botched gun operation known as “Fast and Furious,” ATF officials considered changing the agency’s name to something along the lines of the “Violent Crime Bureau,” according to law enforcement officials. The relaunch fell by the wayside, in no small part because it would have to be approved by Congress.

ATF agents are still praised by police officials across the country for their professionalism, ballistics skills and willingness to share information and credit in criminal investigations.

“The ATF are always great team players,” said Chuck Wexler, executive director of the Police Executive Research Forum. “They’re very good at what they do. You would be hard-pressed to find any police chief in America that doesn’t think the ATF doesn’t have a huge impact in their community in fighting gun crime.”

But the agency has suffered a series of missteps. In 1992, ATF agents were involved in a deadly shootout with a family in Ruby Ridge, Idaho. A year later, an ATF raid on the Branch Davidian compound in Waco, Tex., led to the fatal shooting of four federal agents and the death of more than 75 men, women and children inside the compound.

Then came Fast and Furious, the Phoenix operation that allowed weapons to pass into the hands of suspected firearms smugglers so that they could be traced to the upper levels of Mexican drug cartels. The ATF lost track of about 2,000 guns, including AK-47-style rifles. Two guns linked to a suspected trafficker were found at the scene of the fatal shooting of Border Patrol agent Brian Terry in December 2010.

With the ATF reeling from the controversy, Attorney General Eric H. Holder Jr. appointed Jones, the U.S. attorney from Minnesota, as the acting director. Jones agreed to try to juggle that job with his position as U.S. attorney, commuting back and forth, but ATF officials said the move has not been sufficient.